


(i solemnly swear i'm) up to no good

by fangirlscribbles



Category: Shadowhunters (TV)
Genre: I have no excuses, I'm Sorry, M/M, Plot What Plot/Porn Without Plot, borderline exhibitionism??, either that or just takes place like immediately after their wedding it's up to you, jace is mentioned, no beta we die like men, or more like not giving a fuck, possibly very slightly canon divergent
Language: English
Status: Completed
Published: 2019-05-08
Updated: 2019-05-08
Packaged: 2020-02-28 10:54:26
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,493
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18755017
Author URL: https://archiveofourown.org/users/fangirlscribbles/pseuds/fangirlscribbles
Summary: Sometimes, Magnus mused, it seemed the universe conspired against him. He was staying at the Institute for the night, which usually wasn’t a problem. Tonight, however, Jace was sleeping in the room next to Alec’s since his own was currently wrecked for some reason or other – Magnus hadn’t listened, as he didn’t particularly care – and the wall the two rooms shared was notoriously thin. Which, again, shouldn’t have been a problem, but the way Alec kept pulling away from Magnus’s mouth and hands made it clear that it was.“Oh, please. We can be quiet, can’t we?” Magnus whispered into the space between their mouths. He’d been on edge all day, not to mention that he could tell that Alec was, too, and he was not ready to give this up just yet.“No,” Alec almost whined, “we can’t. You know that.”And damn it all to Edom, if Alec wasn’t right.





	(i solemnly swear i'm) up to no good

Sometimes, Magnus mused, it seemed the universe conspired against him. He was staying at the Institute for the night, which usually wasn’t a problem. Tonight, however, Jace was sleeping in the room next to Alec’s since his own was currently wrecked for some reason or other – Magnus hadn’t listened, as he didn’t particularly care – and the wall the two rooms shared was notoriously thin. Which, again, shouldn’t have been a problem, but the way Alec kept pulling away from Magnus’s mouth and hands made it clear that it _was_.

 

“Oh, please. We can be quiet, can’t we?” Magnus whispered into the space between their mouths. He’d been on edge all day, not to mention that he could tell that Alec was, too, and he was not ready to give this up just yet.

 

“ _No_ ,” Alec almost whined, “we can’t. You know that.”

 

And damn it all to Edom, if Alec wasn’t right. Magnus, with his many years of practice, might manage it – _maybe_ , because Alec had a certain way of driving him absolutely insane – but Alec? He’d never really had to be quiet, and Magnus had spent hours upon hours upon hours learning exactly how to coax the most delicious noises from his mouth.

 

“Mm, maybe _you_ can’t, but why should _I_ be punished for that?”

 

When it became clear that Alec wasn’t going to answer Magnus sighed. He leaned in from where he was propped on an elbow next to Alec to lick a stripe along his neck anyway, smirking to himself when he could actually feel how hard Alec had to work to hold back his moan. If nothing else was happening tonight, at least he’d have that.

 

“We haven’t had sex in weeks, and this happens?” he said, tone dry and displeased. “This is some bullshit. Can’t we just Portal back to my place?”

 

Alec chuckled, rather breathily. Magnus would be lying if he said it didn’t send a curl of heat flaring in his stomach.

 

“We can’t, and you know why.”

 

Magnus hummed, letting his mouth continue its journey across Alec’s neck and collarbones. He did know why; there was currently a rather important prisoner held in the bowels of the Institute, which required Alec to be on-site at all times until the transfer to Idris was complete. In fact, the transfer in question would require Magnus’s assistance as well, which was why he had agreed to stay over in the first place. Due to the stupidity of time zones and the world’s general awfulness, the transfer had to happen rather early in the morning.

 

“Also,” Alec continued, half-heartedly pushing at Magnus’s head, “it hasn’t been _weeks_.”

 

In retaliation for being pushed away, Magnus bit into Alec’s collarbone before he drew back, eliciting a sharp gasp.

 

“Oh, well, it feels like it’s been weeks. Aren’t there any runes for this kind of occasion anyway?”

 

Alec squinted up at him. He was looking quite beautiful at the moment, in Magnus’s opinion; cheeks flushed, chest heaving, lips glistening with saliva, his own and Magnus’s. _God_ , Magnus thought, his half-hard erection twitching at the sight, _my husband is beautiful._

 

“Why are you looking at me like that?” Alec said, instead of answering the question. Magnus took that to mean _no_ , or _I don’t know_ , or possibly even _I can’t think straight right now so I don’t care_. The hardness he could feel against the thigh he had across Alec’s hips certainly spoke to the last option.

 

Magnus smiled softly down at him, running a finger along his nose. “You’re beautiful.”

 

Alec’s eyes closed and his cheeks reddened further, even as his lips curled in a pleased smile.

 

“Magnus,” he said in the patient tone of someone explaining something to a toddler, “we’ve been through this. You’re the beautiful one.”

 

Unable to resist, Magnus leaned in and pressed a gentle kiss to Alec’s lips. It deepened more and faster than he’d planned, drawing pleasured sighs from both of them and making Alec shift and arch his body against Magnus in a way the warlock rather appreciated.

 

“God, Alec, you’re going to be the death of me,” he said against his mouth. Alec just hummed in reply, kissing him again and again, hands coming up to tangle in Magnus’s hair.

 

When Alec’s hands started wandering down Magnus’s body again, inching up the black tank top he was wearing, Magnus pulled away.

 

“I thought we weren’t going to do anything tonight?” he teased, grinning when Alec clenched his eyes closed in frustration.

 

“Maybe— maybe just a little,” the Shadowhunter amended, using the hand currently pressed against Magnus’s back to press the warlock down against him again.

 

“Mm,” Magnus said, pulling back from Alec’s heated kiss just enough to speak, “how much, exactly, is a little?”

 

Alec grunted, clearly ruffled now. His hands moved down to grip Magnus’s hips instead, his own thrusting up to meet them. Magnus’s eyes closed at that, mouth falling open on a gasp.

 

“I don’t know. Guess we’ll just have to see.”

 

With that, Alec rolled them over, so he was on top and _oh_ , Magnus liked this. It was quite rare that Alec took command in the bedroom, preferring to let Magnus, the more experienced of the two, take the lead.

 

Magnus practically purred when Alec trailed kisses from his mouth along his cheek to his neck, nipping at his earlobe with his teeth.

 

“By the Angel,” Alec breathed into Magnus’s ear, his hot breath raising goosebumps along Magnus’s entire side, “I haven’t been this turned on in a long time.”

 

“Uh-huh,” Magnus said, more focused on getting Alec’s t-shirt off than trying to hold a conversation.

 

“Yeah.” Alec threw his top on the floor without a care in the world where it landed, working on Magnus’s next. “Yeah, this is happening. _Fuck_.”

 

Magnus’s breath hitched; if it was rare that Alec took control, it was rarer still that he got so worked up that he started swearing. When he looked up into Alec’s face, he found his expression serious, and the pupils of his eyes blown so wide there was barely any iris visible at all.

 

“ _Alec_ ,” he said, clearly too loud for the Shadowhunter’s liking as he glanced toward the wall his and the next room shared, pressing two fingers against Magnus’s lips, gentler than he’d expected from the look on Alec’s face.

 

“Hush, love. I’ll take care of you.”

 

And god, if that deep, raspy voice didn’t just make Magnus want to moan louder. He swallowed it down with a bit of a struggle, closing his eyes as Alec started kissing his way down Magnus’s chest.

 

By the time Magnus was naked and Alec’s hot breath was ghosting over his cock, he was painfully hard and struggling more than expected to stay quiet.

 

“I thought I was the loud one?” Alec said as he pulled away from Magnus’s erection, and his tone was more teasing than it had any right to be.

 

Magnus bit the inside of his cheek nearly hard enough to draw blood to hold back a groan, reaching a hand down to tangle in Alec’s hair to try and distract himself.

 

“Less talking, more sucking.”

 

“So bossy,” Alec muttered, but did as he was asked.

 

And, okay, maybe this _hadn’t_ been the best idea after all, Magnus thought as his head arched back into his pillow, mouth falling open with loud, harsh gasps. One of Alec’s hands stroked up Magnus’s hip in a calming gesture, and Magnus gratefully grabbed it in his free hand, clutching Alec’s fingers between his own hard enough that it had to hurt. Alec said nothing about it, but possibly that was just because his mouth was busy elsewhere, pulling off to mouth down the side of Magnus’s cock instead, licking his balls once he got to the base.

 

Magnus grit his teeth together, pulled on Alec’s hair hard enough to elicit a sound that was part pain but mostly pleasure. “Why aren’t you naked yet?”

 

Following the insistent tugging on his hair, Alec came up to press wet, open-mouthed kisses against Magnus’s lips and cheeks and neck.

 

“I don’t know,” he said. “Are you going to fix it?”

 

Magnus pulled away and opened his eyes long enough to grin gleefully at Alec, snapping his fingers and banishing Alec’s boxer briefs all the way back to his – their – loft. Not that Alec would even notice until they were done, caught up as he was with roaming his hands all over Magnus’s body and pressing lips and teeth and tongue against all the sensitive spots he could reach.

 

Magnus snapped his fingers again. “I thought this might be easier with lube.”

 

Alec barely paused to quirk an appreciative eyebrow at his husband as he accepted the small bottle Magnus offered to him.

 

“By the Angel,” he said, way too casually considering he was currently slathering a liberal amount of lube on his fingers, “I love you.”

 

Then he pressed a finger inside of Magnus just as he opened his mouth to reply, and whatever Magnus was going to say got cut off with a moan. Alec was immediately there to silence him with his own mouth, but he was a couple seconds too late.

 

“Damn it, I knew this was going to happen,” Alec said, even as he pushed a second finger in alongside the first.

 

“Mm-hmm,” Magnus agreed, rather breathily and unable to focus. “ _More_ , Alec, please.”

 

Alec’s head dropped down to Magnus’s shoulder for a second, but came back up again just as quickly. “ _God_ , Magnus,” he groaned, “look at you.” He curved his fingers against Magnus’s prostate, and all the warlock could do in reply was moan.

 

“Fuck, I love you,” Alec continued, adding a third finger and fucking into Magnus in earnest now. Magnus’s hands grabbed the sheets and held on for dear life, his head pressing back into the pillow and his teeth pressing into his lip in an attempt to keep quiet that was by now rather half-hearted, not to mention futile.

 

All Magnus could manage in response was a nonsensical “yeah, yeah, fuck, me too, fuck me,” and Alec actually laughed – although, to be fair, it sounded like he wasn’t wholly unaffected by the words.

 

“Your wish is my command,” he said, already slicking himself up, breath stuttering a little as he stroked himself.

 

“Alexander,” Magnus murmured, giving his husband an appreciative once-over from where he was fisting his cock up to his eyes, dark on Magnus’s face, “you are insanely hot, did you know?”

 

Alec’s eyes closed for a second, his teeth biting into his bottom lip. Magnus let out an appreciative noise at the picture he made, one hand coming up to lightly stroke Alec’s thigh.

 

“Yeah? I’m glad you like it,” Alec said, but didn’t give Magnus any chance to reply further as he dropped down on his back next to Magnus, gesturing for him to get on top. “Come on, I want you to ride me.”

 

Magnus actually moaned at the suggestion. “Your wish is my command,” he echoed, moving to straddle Alec’s hips. He took hold of Alec’s cock, giving it a few strokes before guiding it to his entrance, continuing, “God, I love seeing you like this, spread out underneath me and just waiting…”

 

He rubbed the tip of Alec’s erection against himself a few times, just to tease, until the grip Alec had on his hips was near bruising in strength, and he was clenching his jaw so hard Magnus was a little worried for his teeth. Then he sank down slowly, slowly, fairly certain neither of were breathing until he was fully seated; Alec, clearly having given up on being quiet and keeping their activities to himself, let out a loud, throaty groan, and Magnus drew a deep, stuttering breath.

 

“Please,” Alec panted, eyes closed, “please don’t move for a second, I—”

 

“Yeah, me too.”

 

They stayed like that for a minute, just breathing, until they regained their bearings somewhat, and Alec rolled his hips up, fucking impossibly deeper into Magnus. Magnus fell forward with the loudest moan yet, bracing himself with his hands on Alec’s biceps.

 

“ _Shit_ , Alec, don’t stop,” he said, curling forward further until he was half lying on top of Alec, supporting himself on his forearms on either side of Alec’s head so he could bury his face into the crook of Alec’s shoulder as the Shadowhunter set a punishing pace.

 

Alec moaned, one hand leaving its grip on Magnus’s hip so he could move his arm up to cradle his back.

 

“God, babe, you feel so good around me.”

 

All Magnus offered in response was a string on unintelligible noises as he straightened up just enough so he could get some leverage to move his hips against Alec’s, meeting his thrusts a little out of rhythm.

 

“Touch me,” he managed to grind out between teeth clenched against moans bordering on screams, “please, Alexander, God, _touch me_.”

 

“Yeah?” Alec wrapped his hand around Magnus’s cock, jerking him off in time with their frantic thrusting; tonight was not a night for slow or gentle. “Yeah, you gonna come for me?”

 

“Ngh.” Magnus’s back arched as he slammed his hips down against Alec’s that bit harder, twisting a little as he did and suddenly Alec’s cock was _right_ up against his prostate. “Yeah, fu— _Alec_!”

 

He fell forward again, mouth open in a silent scream against Alec’s neck as his cock pulsed, thick spurts of come landing on Alec’s stomach. Alec, alternately moaning and gasping desperately, grabbed his hips with both hands again as he thrust up once, then twice horribly uncoordinatedly, before he came, his whole body going taut.

 

As Alec relaxed back into the bed and Magnus went boneless on top of him, there was a minute of blissed out silence, the only sound in the room their heavy breathing. Then there was a sudden, dull thud against the wall.

 

“Are you guys done already so I can go to sleep?” Jace called, voice annoyed but less disgusted than expected.

 

“Yeah,” Alec said, grimacing with embarrassment but chuckling helplessly, “sorry, man.”

 

In the morning, Jace glared at them and grumbled something about having to go on late-night excursions to avoid learning more than he ever wanted to know about his parabatai’s sex life. Alec’s face went spectacularly red, but he and Magnus were equally relieved to realize that Jace hadn’t actually heard everything that had gone down the night before.

 

“It won’t happen again,” Alec promised, voice barely above a whisper so Isabelle and Clary wouldn’t hear what they were saying.

 

Jace punched his shoulder. “Don’t worry, man, we’re cool. I get it. Payback for when I stayed with Magnus, right?”

 

Magnus and Alec glanced at each other, suddenly smirking.

 

“Right,” Alec agreed.

 

Both he and Magnus silently decided not to mention that they had completely forgotten about that time in their lives. Perhaps it would come in handy in future  _situations_.

**Author's Note:**

> Look, I am super shitty at replying to comments, but I read and love them all and both kudos and comments make me so happy! Concrit is welcome as well, if you have any.  
> If you like this fic, you can also [reblog it on tumblr](https://finleysfins.tumblr.com/post/184733444319/i-solemnly-swear-im-up-to-no-good) :')


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